On a Friday of intriguing tyre conundrums in Montreal, Mercedes chose to eschew the use of Pirelli's quickest tyre, the hypersofts, and run exclusively on the supersoft and ultrasoft compounds in practice.
"This is a power circuit so it was our target (to have the new engine) and it definitely would have been helpful", said Hamilton, who is aiming for a record-equalling seventh victory in Canada tomorrow.
"I don't think the hypersoft is a good race tyre". You could see in Monaco that we have a great vehicle and it's very unfortunate that we don't have the top speed to compete all the time. So constantly today going into that corner I was struggling to get the auto stopped, be it front locking or rear locking, so it was quite messy.
Red Bull again look very competitive thanks to the Hypersoft tyre and had good speed on the straights but Mercedes also look strong without really revealing their hand thanks to their different tyre approach.
Lewis Hamilton slipped up in qualifying.
Hamilton said: "I believe that the gap in the time sheets is down to the different tyre choices today, but we will find out tomorrow [Saturday]".
"From our testing, we had in Abu Dhabi [last December] particularly, that's what led us to the decisions we made and we stick with those".
"It's very hard. We have a great auto but our whole package is not the best on every single track and we just have to accept that".
"But it was a combination of things".
"Compared to a year ago, we have another vehicle and the approach is, of course, also different".
"I was running a bit out of juice at the end", said Vettel over team radio.
Asked about his driving style on Thursday after arriving in Montreal, he said, "I get really exhausted of all the questions". He spent most of the second practice session in the pits waiting for his team to iron out an electrical issue, and managed just 17 laps in the session.
Pole position qualifier Sebastian Vettel talks in the press conference after qualifying.
"Certainly not having given the drivers enough track time on the hyper, if we could have changed it now on the weekend we would have changed it".
"Hindsight is a great thing so naturally it would have been great to have been able to try the hyper today", Hamilton said in the paddock.
Toro Rosso are also hoping for a lift from a newly upgraded Honda engine and it is working with Brendon Hartley 12th in the afternoon after teammate Pierre Gasly had been in the top 10 in the opening practice session. If you miss out on the tiniest of upgrades, the smallest of mistakes will be penalised. This is going to make the difference in winning or losing the weekend.